Simplify the following expression: $z = \dfrac{7a}{9} \div \dfrac{2a}{4}$
Dividing by an expression is the same as multiplying by its inverse. $z = \dfrac{7a}{9} \times \dfrac{4}{2a}$ When multiplying fractions, we multiply the numerators and the denominators. $z = \dfrac{ 7a \times 4 } { 9 \times 2a}$ $z = \dfrac{28a}{18a}$ Simplify: $z = \dfrac{14}{9}$